An orthogonal frequency division multiplexing (OFDM) technology currently is a widely used technology, and a technology used by the current hottest communications standard Long Term Evolution (LTE) is the OFDM technology, where in the OFDM technology, a channel is divided into several orthogonal sub-channels, and data is modulated onto each sub-channel for transmission. Orthogonal signals may be separated at a receive end by using a related technology, which may reduce mutual interference among sub-channels, and also make it easier to receive the signals.
The OFDM technology has many advantages, for example, a strong anti-attenuation capability and high frequency utilization. However, an OFDM signal is obtained by adding together multiple subcarrier signals that are independent and modulated, and such a composite signal may generate relatively high peak power, that is, a peak to average power ratio (PAPR) is extremely high, which causes reduction in power amplifier efficiency. To improve performance of an OFDM system, a base station generally needs to process a signal by using a power control method, such as PAPR reduction and control of error vector magnitude (EVM).
However, in an existing power control method, same processing is performed on signals at an entire frequency band. The entire frequency band may include modulated signals of different orders (that is, signals of different users), and the modulated signals of different orders have different requirements for modulation precision. In an existing power control and processing method, different processing cannot be performed on different signals of different orders to meet different demands. Signals of high order (that is, a near-end user) generally has poorer precision, and users at different distances cannot be simultaneously considered; therefore, overall performance of the OFDM system is limited.